US11073675B2 - Camera module autofocus actuator - Google Patents

Camera module autofocus actuator Download PDF

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US11073675B2
US11073675B2 US16/607,152 US201816607152A US11073675B2 US 11073675 B2 US11073675 B2 US 11073675B2 US 201816607152 A US201816607152 A US 201816607152A US 11073675 B2 US11073675 B2 US 11073675B2
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Prior art keywords
return elastic
lens carrier
support member
shape memory
memory alloy
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US20200041872A1 (en
Inventor
Markus Köpfer
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Actuator Solutions GmbH
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Actuator Solutions GmbH
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B3/00—Focusing arrangements of general interest for cameras, projectors or printers
    • G03B3/10—Power-operated focusing
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B17/00—Details of cameras or camera bodies; Accessories therefor
    • G03B17/02—Bodies
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03G—SPRING, WEIGHT, INERTIA OR LIKE MOTORS; MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOT OTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISE PROVIDED FOR
    • F03G7/00—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for
    • F03G7/06—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like
    • F03G7/061—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like characterised by the actuating element
    • F03G7/0614—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like characterised by the actuating element using shape memory elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
    • G02B7/04—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification
    • G02B7/09—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification adapted for automatic focusing or varying magnification
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B17/00—Details of cameras or camera bodies; Accessories therefor
    • G03B17/02—Bodies
    • G03B17/12—Bodies with means for supporting objectives, supplementary lenses, filters, masks, or turrets
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03G—SPRING, WEIGHT, INERTIA OR LIKE MOTORS; MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOT OTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISE PROVIDED FOR
    • F03G7/00—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for
    • F03G7/06—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like
    • F03G7/065—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like using a shape memory element
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B13/00—Viewfinders; Focusing aids for cameras; Means for focusing for cameras; Autofocus systems for cameras
    • G03B13/32—Means for focusing
    • G03B13/34—Power focusing
    • G03B13/36—Autofocus systems
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B2205/00—Adjustment of optical system relative to image or object surface other than for focusing
    • G03B2205/0053—Driving means for the movement of one or more optical element
    • G03B2205/0076—Driving means for the movement of one or more optical element using shape memory alloys

Definitions

  • the present invention is inherent to a novel and improved autofocus (AF) actuator for camera modules incorporating one or more shape memory alloy wires as actuating element(s), with particular reference to cellular phones camera modules.
  • AF autofocus
  • shape memory alloy wires as actuating elements provides various advantages with respect to other actuating systems in terms of weight, power consumption, costs.
  • EP 1999507 for example, is concerned with maximizing the degree of movement of the lens carrier along the optical axis within the practical constraint of the limited size of the actuation apparatus.
  • the solution proposed therein is the use of two lengths of SMA wire in a pair coupled to one of the lens carrier and the support member at a common point and extending therefrom at acute angles relative to the optical axis of opposite sign as viewed radially of the optical axis.
  • the acute angle of the wires provides the gearing effect described which increases the degree of movement as compared to wires extending along the optical axis.
  • arranging lengths of SMA wire at an acute angle to the optical axis provides the disadvantage that the SMA wire also provides off-axis forces with a component perpendicular to the optical axis that tend to laterally displace or tilt the lens carrier.
  • Such off-axis forces can be resisted by the design of the suspension system that supports the lens carrier on the support member and guides its movement along the optical axis, however such a suspension system tends to have high frictional forces and is not compact.
  • a suspension system is a bearing in which a movable bearing element contacts and runs along a track, with the off-axis resistance provided by the reaction between the bearing element and the track, but a bearing is a type of suspension system having relatively high frictional forces and being of relatively large size.
  • an AF camera module including a base with a cylindrical member extending therefrom that is provided with two opposite slits formed in the wall of the cylindrical member and extending parallel to the optical axis of a lens carrier slidably mounted within the cylindrical member.
  • Two supporting bars protrude outward from an upper end of the cylindrical member at portions above the slits, and a hook bar protrudes from the outer circumference of the cylindrical member midway between the slits.
  • Protrusions are formed on an outer circumference of the lens carrier to extend out of the cylindrical member through the slits, and springs formed of conductive material are respectively installed on outer end portions of the protrusions with their lower ends fixed on a top surface of the base and their upper ends fixed to the protrusions.
  • a first and a second end of a SMA wire are respectively connected to the protrusions and electrically connected to the springs such that when electric power is applied to the springs, current flows along the SMA wire which gets shorter.
  • the SMA wire extends from the first end fixed on one of the protrusions to the supporting bar above it, and is bent downward at said supporting bar to extend down to the hook bar around which it is bent upward to extend up to the other opposite supporting bar, where it is again bent downward to extend down to the other protrusion such that the second end of the SMA wire is fixed to said protrusion.
  • the SMA wire does not provide off-axis forces with a component perpendicular to the optical axis since such forces are discharged onto the supporting bars and the hook bar that are integral with the base, however the tortuous path of the SMA wire with three bends around said bars negatively affects the reliability and effectiveness of the camera module due to the concentrations of stress and friction at those bending positions.
  • the SMA wires connect the support member to the lens carrier and follow a path, in a plane perpendicular to the optical axis, with a 90° bend in the middle portion that implies a stress concentration.
  • EP 2003489 discloses a somewhat similar AF mechanism including a base plate and a top plate with a lens carrier movable therebetween that is biased by a top spring towards the base plate, and with a drive arm having a pantograph structure that holds the lens carrier.
  • a single SMA wire is formed like a square ring and is extended on two displacement input sections of the drive arm, located at first two opposite corners of said square ring, and around a tension guide mounted between the top and bottom plates at a third corner opposite to the fourth corner where both ends of the SMA wire are fixed, through two SMA fixing members serving also as electrodes, onto a support member mounted on the bottom plate.
  • the SMA wire connects the support member (base plate) to the lens carrier (through the drive arm) and follows a path, in a plane perpendicular to the optical axis, with a 90° bend in the middle portion (at the tension guide) that implies a stress concentration.
  • the object of the present invention is therefore to overcome the drawbacks still present in the prior art in terms of cost, complexity, reliability, stress concentration and frictional forces in a SMA-based autofocus, while providing a compact structure which maximizes the movement of the lens carrier.
  • substantially in the present specification indicates the fact that there may be minimal variations, such as standard manufacturing tolerances that are typically less than 5%, which can involve constitutional parameters such as width, length, thickness, diameter and so on.
  • a first important advantage of the structure of this actuator is that it permits to fully exploit and amplify the length change of the activated SMA wire(s) without substantially generating unbalanced off-axis forces that stress the structure and cause high friction during the movements, whereby prior art rolling members can be dispensed with.
  • a second significant advantage resides in the fact that the SMA wire(s) do not bend around unyielding members that cause a stress concentration in the wire(s) upon activation thereof, thus increasing the reliability and operational life of the actuator.
  • a third advantage is that the structure of such an actuator is simpler and therefore cheaper to manufacture, with fewer and more robust components that provide greater reliability.
  • Still another advantage results also from a careful selection of the materials for the lens carrier and the support member, which materials guarantee a smooth sliding of the lens carrier on the support member with low friction, low particle generation, low stick slip, high resistance for drop test and a tight static and dynamic tilt tolerance.
  • FIGS. 1 a and 1 b are top perspective views of two possible arrangements for the sliding coupling of the support member and lens carrier of an AF actuator according to the present invention
  • FIGS. 2 a and 2 b are front views of a first embodiment of the AF actuator with the SMA wires in the non-activated and activated conditions respectively,
  • FIGS. 3 a and 3 b are top perspective views of a second embodiment of the AF actuator with the SMA wires in the non-activated and activated conditions respectively,
  • FIGS. 4 a and 4 b are schematic front views of a third embodiment of the AF actuator with the SMA wires in the non-activated and activated conditions respectively,
  • FIGS. 5 a and 5 b are front views of a fourth embodiment of the AF actuator with the SMA wires in the non-activated and activated conditions respectively,
  • FIGS. 6 a and 6 b are schematic top perspective views of a fifth embodiment of the AF actuator with a single SMA wire in the non-activated and activated conditions respectively, and
  • FIGS. 7 a and 7 b are front views of a sixth embodiment of the AF actuator with the SMA wires in the non-activated and activated conditions respectively.
  • the dimensions and dimensional ratio of the elements may not be correct and in some cases, such as for example with regards to the shape memory alloy wire diameter, have been altered in order to enhance the drawing comprehension.
  • FIGS. 1 a and 1 b show, in an exploded condition and an assembled condition respectively, two possible arrangements for the sliding coupling of a fixed support member 1 , 1 ′ and a movable lens carrier 2 , 2 ′ that is supported and guided by said support member 1 , 1 ′ to perform a reciprocating motion along an optical axis of the AF actuator.
  • the fixed support member 1 , 1 ′ and the movable lens carrier 2 , 2 ′ are made of plastic material, have a substantially square shape in a plane orthogonal to the optical axis and are slidingly coupled through at least four guide posts 1 a , 1 a ′ that extend parallel to the optical axis from the support member 1 , 1 ′ and engage matching grooves 2 a , 2 a ′ formed on the lens carrier 2 , 2 ′.
  • the post/groove couplings are preferably formed at the corners of the actuator so as to minimize the size thereof, but they could also be located elsewhere in case of particular necessity.
  • the actuator could have a rectangular shape if double optics are used, and additional couplings could be provided on the long sides between the two sets of lenses.
  • the fixed support member 1 , 1 ′ and the movable lens carrier 2 , 2 ′ are injection molded with high precision molds and with a careful selection of the plastic materials (as to resistance, sliding factor and stability over temperature) in order to achieve dimensional tolerances that guarantee a maximum tilt of 0.08° of the lens carrier when coupled to the support member.
  • the difference between the two arrangements shown in FIGS. 1 a , 1 b is that in the first case the guide posts 1 a are integrally molded on the support member, and therefore are made of plastic, whereas in the second case the guide posts 1 a ′ are metal plates pressed in on the support member 1 ′, such metal plates being stable over temperature and offering the best sliding factor.
  • FIGS. 2 a -2 b , 3 a -3 b , 5 a -5 b and 7 a -7 b show four different embodiments of the present actuator with the sliding coupling between the support member 1 and the lens carrier 2 according to FIG. 1 a , yet it is clear that similar embodiments can be obtained with the sliding coupling between the support member 1 ′ and the lens carrier 2 ′ according to FIG. 1 b.
  • the plastic materials are selected to provide the above-mentioned advantages of low friction, low particle generation, low stick slip and high resistance for drop test, thus helping in dispensing with the rolling members arranged between the support member and the lens carrier that are present in the cited prior art actuators.
  • the applicant found that a good combination of materials is for the support member to be made from polybutylene terephthalate (e.g. Celanex 2002-2 from Celanese Corporation of Irving, Tex., US) and for the lens carrier to be made from copolymer polyoxymethylene (e.g. Hostaform C 27021 also from Celanese Corporation).
  • the first embodiment illustrated in FIGS. 2 a , 2 b of an actuator according to the present invention includes four identical return elastic elements 3 arranged in two pairs with the two elements 3 of each pair being contained in a common plane parallel to the optical axis A, with symmetrically opposite mounting arrangements with respect to the optical axis A, and two straight shape memory alloy wires 4 each of which is mounted, preferably horizontally, between the two elements 3 of a same pair.
  • the front views of these figures shown only one pair of return elastic elements 3 with a relevant shape memory alloy wire 4 , but the same arrangement is found also on the opposite side of the actuator.
  • Each return elastic element 3 includes a flexible strip, preferably made of metal, mounted with a first end 3 a secured to the support member 1 at a lower outermost position and a second end 3 b secured to the lens carrier 2 at a higher innermost position. More specifically, the first end 3 a is slidingly mounted on the support member 1 whereas the second end 3 b is anchored to the lens carrier 2 at a central socket 2 b located along the bottom edge thereof.
  • the actuator In the rest condition of FIG. 2 a the actuator is in the so-called infinity focus position and when the shape memory alloy wires 4 are heated by current passage they shorten and exert a force onto the lens carrier 2 through elements 3 that are pulled closer to each other, thus moving upwards the lens carrier 2 through socket 2 b such that the lens is focused up to the so-called macro position (i.e. focusing on a nearby plane) of FIG. 2 b .
  • Infinity and macro represent the two AF extreme positions and therefore correspond to the amount of adjustment that the AF actuator shall be capable to achieve.
  • the same return elastic elements 3 exerting a vertical return force opposing the SMA traction pull back the lens carrier 2 to the infinity position. It is important to underline that with such an AF actuator configuration according to the present invention the return elastic elements 3 exert a force only in parallel to the optical axis so as to prevent any off-axis force from being generated.
  • a position sensor and readout for example a magnet on the lens carrier 2 and a Hall sensor on the support member 1 , are also present to determine the correct equilibrium position during the AF actuator operation so that a control unit, e.g. a flexible printed circuit board, can provide current to the SMA wires 4 through their terminals for their activation via Joule effect according to the Hall sensor readout.
  • a control unit e.g. a flexible printed circuit board
  • wires 4 are shown connected to the return elastic elements 3 at a position close to their outermost first ends 3 a , wires 4 could also be arranged at a higher position closer to the middle of elements 3 which could be fixed to the support member 1 (i.e. the first ends 3 a would not be slidingly mounted thereon) such that the vertical displacement of the lens carrier 2 would result only from the deformation of the central portions of elements 3 included between the ends of wire 4 .
  • each return elastic element 3 further includes an upright 3 c extending substantially vertically from the mounting position of the first end 3 a up to at least the height at which the mounting position of the second end 3 b is located when the shape memory alloy wire 4 is not activated, the latter being mounted between said uprights 3 c substantially at said height (i.e. wire 4 is horizontally aligned with the second ends 3 b in FIG. 3 a ).
  • this second embodiment is substantially the same as in the first embodiment, i.e. when the shape memory alloy wires 4 are heated by current passage they shorten and pull closer to each other the uprights 3 c which pivot inwards thus causing also the first ends 3 a to pivot inwards and move closer so as to exert a force onto the lens carrier 2 that is moved upwards through socket 2 b ( FIG. 3 b ).
  • the return elastic elements 3 pull back the lens carrier 2 to the rest position of FIG. 3 a.
  • each return elastic element 5 consists of a horizontal V-shaped flexible connector mounted with its vertex 5 a at an outermost position with respect to its ends 5 b , which are preferably connected to the support member 1 and to the lens carrier 2 at vertically aligned positions.
  • each shape memory alloy wire 4 is preferably mounted between the vertices 5 a of the two horizontal V-shaped flexible connectors 5 of each pair, but it could also be mounted horizontally at a different height or it could be mounted slanted.
  • this third embodiment is substantially the same as in the previous embodiments, i.e. when the shape memory alloy wires 4 are heated by current passage they shorten and pull vertices 5 a closer to each other thus widening the V shape of each horizontal V-shaped flexible connector 5 and causing the lens carrier 2 to move upwards through ends 5 b ( FIG. 4 b ).
  • the return elastic elements 5 pull back the lens carrier 2 to the rest position of FIG. 4 a.
  • the exact shape and position of the two return elastic elements 5 of each pair is obviously variable according to the specific requirements of the actuator, in that the two elements 5 could be closer and/or the sides of their V shapes could be longer.
  • FIGS. 5 a , 5 b a variant of such an arrangement is shown in the fourth embodiment illustrated in FIGS. 5 a , 5 b where the ends 5 b come into contact so that the two return elastic elements 5 of each pair are merged into a single rhomb-shaped elastic element 6 .
  • this embodiment includes only two identical rhomb-shaped return elastic elements 6 mounted with a bottom vertex 6 a secured to the support member 1 and vertically aligned to a top vertex 6 b secured to the lens carrier 2 , close to the top edge thereof, and two straight shape memory alloy wires 4 each of which is mounted within one of the rhomb-shaped return elastic elements 6 , preferably between two horizontally aligned intermediate vertices 6 c thereof (but it could also be mounted horizontally at a different height or it could be mounted slanted).
  • this fourth embodiment is substantially the same as in the third embodiment, i.e. when the shape memory alloy wires 4 are heated by current passage they shorten and pull vertices 6 c closer to each other thus making narrower and higher the rhomb shape of each return elastic element 6 and causing the lens carrier 2 to move upwards through the top vertices 6 b ( FIG. 5 b ).
  • the return elastic elements 6 pull back the lens carrier 2 to the rest position of FIG. 5 a.
  • the lens carrier (not shown) is located between the two elements 5 of each pair, in this case it is not possible to arrange a SMA wire between the vertices 5 a of the two elements 5 of each pair whereby a single shape memory alloy wire 7 is horizontally mounted to sequentially connect the vertices 5 a of all four elements 5 along the periphery of the actuator (but it could also be mounted horizontally at a different height).
  • this fifth embodiment is substantially the same as in the third embodiment, i.e. when the shape memory alloy wire 7 is heated by current passage it shortens and pulls all four vertices 5 a towards the optical axis making them closer to each other thus widening the V shape of each return elastic element 5 and causing the lens carrier 2 to move upwards through ends 5 b ( FIG. 6 b ). Upon deactivation of the SMA wire 7 , the return elastic elements 5 pull back the lens carrier 2 to the rest position of FIG. 6 a.
  • FIGS. 7 a , 7 b The sixth and last embodiment illustrated in FIGS. 7 a , 7 b is similar to the fourth embodiment in that it includes only two identical lever-rod return elastic elements 8 , each of which includes a lever 8 a pivoted on the support member 1 and carrying a rod 8 b pivoted between said lever 8 a and the lens carrier 2 at a central position of the latter, and two straight shape memory alloy wires 4 each of which is secured between the support member 1 and lever 8 a .
  • the pivoting connections 9 a , 9 b , 9 c between these elements are realized through film hinges made out of plastic that also act as torsional springs, so as to provide a return force upon deactivation of the SMA wire 4 .
  • lever 8 a is pivoted substantially horizontally on the support member 1 through a first pivot 9 a located at the top of an upright 1 b extending on the left of the actuator's centre from the base of the support member 1 up to the top edge of the lens carrier 2 .
  • rod 8 b is pivoted almost vertically between the right end of lever 8 a , through a second pivot 9 b , and a horizontally central portion of the lens carrier 2 , through a third pivot 9 c , while the SMA wire 4 is secured between the right corner of the support member 1 , close to the base of post 1 a , and the left end of lever 8 a so as to maximize its extension.
  • lever 8 a could be pivoted directly on the lens carrier 2 through the second pivot 9 b , thus dispensing with rod 8 b and the third pivot 9 c , but since the rotation of lever 8 a around the first pivot 9 a will also result in a little horizontal shift of the secondo pivot 9 b that would generate off-axis forces and torsional effects on the lens carrier 2 , the presence of rod 8 b is required to obtain a purely axial force of the return elastic elements 8 .
  • the SMA wire(s) 4 has/have a very simple straight configuration that provides the maximum reliability and effectiveness, and even in the fifth embodiment the annular SMA wire 7 is bent around the yielding return elastic elements 5 that do not cause a stress concentration upon activation of the SMA wire.
  • the AF actuator according to the present invention is not restricted to a specific type of shape memory alloy wires, and any shape memory alloy wires activated by Joule effect may be usefully employed. Having said that, preferred is the use of shape memory alloy wires made with Ni—Ti alloys widely known in the field with the name of Nitinol, with diameters ranging from 10 ⁇ m to 200 ⁇ m (preferably from 30 ⁇ m to 75 ⁇ m) and commercially available from a variety of sources, for examples the wires sold under the trade name Smartflex by SAES Getters S.p.A.
  • the material of the V-shaped connectors 5 and rhomb-shaped connectors 6 used in the third to fifth embodiments it is not restricted to any particular one provided that it has enough resistance to a high number of deformations when pulled by the SMA wire.
  • Preferred materials are fiberglass reinforced plastics (FRP), i.e. a type of fiber-reinforced plastic where the reinforcement fiber is specifically glass fiber, most preferably with a Young's modulus comprised between 14 and 15 GPa.
  • the present AF actuator also preferably includes safety features that make it more reliable and resistant to mechanical failure by providing each shape memory alloy wire 4 , preferably at one end thereof, with a spring (not shown) having such a stiffness that in the normal actuator operation it acts as a rigid connection member.
  • said spring acts as a fail-safe member that provides an elongation sufficient to absorb the contraction of the shape memory alloy wire 4 in case the latter is forced to operate on a stuck lens carrier 2 that is unable to move.
  • wire 4 can withstand a stress not much higher than 450 MPa the spring will be selected to have a starting stress level of 450 MPa to activate, whereas before this stress level it will not significantly elongate.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Optics & Photonics (AREA)
  • Lens Barrels (AREA)
US16/607,152 2017-05-04 2018-04-20 Camera module autofocus actuator Active 2038-07-22 US11073675B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
IT102017000048138A IT201700048138A1 (it) 2017-05-04 2017-05-04 Attuatore per auto-focus di modulo di fotocamera
IT102017000048138 2017-05-04
PCT/IB2018/052773 WO2018203173A1 (en) 2017-05-04 2018-04-20 Camera module autofocus actuator

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US20200041872A1 US20200041872A1 (en) 2020-02-06
US11073675B2 true US11073675B2 (en) 2021-07-27

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US (1) US11073675B2 (zh)
EP (1) EP3619576B1 (zh)
JP (1) JP7001713B2 (zh)
KR (1) KR102298464B1 (zh)
CN (1) CN110603487B (zh)
IT (1) IT201700048138A1 (zh)
TW (1) TWI766011B (zh)
WO (1) WO2018203173A1 (zh)

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GB201801993D0 (en) * 2018-02-07 2018-03-28 Cambridge Mechatronics Ltd SMA AF Plain Bearings
KR102139770B1 (ko) * 2018-11-05 2020-08-11 삼성전기주식회사 렌즈 모듈 및 이를 구비하는 카메라 모듈
CN114127607B (zh) * 2019-07-01 2023-02-03 华为技术有限公司 用于摄像头模块的线性执行器
CN112433332A (zh) * 2019-08-09 2021-03-02 新思考电机有限公司 驱动装置、照相装置以及电子设备
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